Indwelling catheters are predominantly manufactured from natural and synthetic rubber latexes. They are made of nonconducting materials. Thin films of certain metals on nonconducting substrates can have important commercial applications. Thin films of conducting metals on transparent substrates are used in electronic display devices. Thin films can be used to reflect heat in solar shading or other solar devices, and to filter radiation from sunlight. A thin film can reduce the incidence of infection caused by a device that is introduced into the human body, when the film is coated onto the device before introduction into the body. Thin films are used in packaging as a vapor barrier coating. These applications are only illustrative of the thousands of uses of thin films, and are not limiting of their uses.
U.S. Pat. No. 6,224,983 to Sodervall et al., which is incorporated by reference herein in its entirety, teaches that metallic silver can be deposited upon the surface of a nonconducting substrate using a multi-step wet deposition process. The surface is cleaned, and then activated in an aqueous solution containing stannous ion. The silver is deposited as a colloidal material from an aqueous solution of a silver-containing salt, a reduction agent that reduces the salt to form the metallic silver, and a deposition control agent that prevents the silver from nucleating throughout the solution. After the substrate is coated, the coating is stabilized in an aqueous solution of a salt of a metal from the platinum group or gold, dissolved in dilute hydrochloric acid. The process is particularly effective for depositing uniform films of 2 to 2000 Angstroms thickness, which strongly adhere to the substrate.
U.S. Pat. No. 5,747,178 to Sodervall et al., which is incorporated by reference herein in its entirety, is directed to deposition of a silver layer on nonconducting substrates. U.S. Pat. No. 5,747,178 discloses a process for depositing thin, uniform layers of silver onto a wide variety of nonconducting substrates. The silver layer is disclosed as being adherent and effective in various uses, including, for example, antimicrobial medical applications, barrier packaging, and optical filters. The process can be performed at ambient temperature or, at most, slightly elevated temperature, using conventional industrial chemical procedures. U.S. Pat. No. 5,747,178 discloses that it is highly controllable and reproducible, producing virtually identical layers on large numbers of substrates, and that tests have shown that the yields of good quality coated parts using the approach are very high.
U.S. Pat. No. 5,747,178 discloses an approach to depositing a thin, uniform layer of silver, preferably 2 to 2000 Angstroms thick, at the rate of about 5-7 Angstroms per second in the deposition solution. U.S. Pat. No. 5,747,178 also discloses that the thickness of the surface layer is readily controlled, and that the resulting silver layer is adherent to the surface of the nonconducting substrate.
Other patents and patent publications including disclosures related to silver films on nonconducting substrates include U.S. Pat. No. 5,320,908; U.S. Pat. No. 5,395,651; U.S. Pat. No. 5,965,204; U.S. Patent Publication No. 2007/237945; U.S. Patent Publication No. 2007/237946; U.S. Patent Publication No. 2009/123733; U.S. Patent Publication No. 2010/028436; and U.S. Patent Publication No. 2011/236441, the contents of each of which are hereby incorporated herein by reference in their entireties.